同級生で彼女の紗和と付き合って半年。喧嘩もせず仲良く過ごし何度かエッチもし関係は良好。今日は部活の朝練を終えてから、何度目かの彼女の家でデート。両親は仕事、兄も大学と聞いていたが紗和のお兄さんが帰ってきた。初めての顔合わせだが、気さくなお兄さんとすぐ打ち解けられた。だが目の前で仲良さげに話す紗和とお兄さん……家族だからと分かっていても、モヤモヤとした嫉妬心が出てしまう。それに気づいた紗和は、テンションが上がってしまいエッチな気分に火がついてしまったらしく……。
I've been dating my classmate Sawa for six months. We get along well, we never fight, and we've had sex a few times; our relationship is going smoothly. Today, after morning practice for my club, we went on a date to her house for the umpteenth time. I'd heard her parents were at work and her brother was at university, but Sawa's brother came home. It was our first time meeting, but I quickly hit it off with her friendly brother. However, seeing Sawa and her brother talking so amicably right in front of me… even though I know they're family, a nagging feeling of jealousy welled up inside me. Noticing this, Sawa seemed to get excited and her mood became sexually charged…

– JavGG.net